Plastic composition of rubber and chlorinated diphenyl



Sept. 13, 1938. F. M. CLARK El" AL PLASTIC COMPOSITION OF RUBBER AND CHLORINATED DIPHENYL Filed Oc t. 19, 1937 00. 0000 muflm o /a .20 3o ya we CHLOE DIPl/E/VYL CONTENT y z mw e San Mi e OCO/W t K n t e A nn r hmm.

In J$T One of the objects of our invention is to proper cent of the same chlorinated diphenyl have 10 embodying our invention, on a straight line, which has been continued only 20 crysta Patented Sept. 13, 1938 I 2,130,264

PLASTIC COMPOSITION OF RUBBER AND GHLORINATED DIPHENYL Frank M. Clark, Pittsfield, Mass., and John H. Koenig, Columbus, Ohio, assignors to General Electric Company, a corporation of New York Application October 19, 1937, Serial No. 169,796 4 Claims. (01. 106-13) This application is a continuation-impart of The'drawing' shows the relation of flow point our prior application, Serial No. 737,951, filed to composition, the flow points being plotted as August 1, 1934. ordinates, and the percentages of resin as The present invention comprises a new comabscissae. 5 position suitable for use for various purposes and, A composition containing 95 per cent chlorl- 5 in particular, for electrical insulation. The comnated diphenyl (60 per cent chlorine) and about positions embodying'our invention are made up 5 per cent rubber is somewhat tacky and has a of rubber and solid halogenated polyphenyl, preffiOW p i t o b t Compositions a erably solid, resinous chlorinated diphenyl. ing about 15 to per cent rubber and 85 to '75 vide compositions which are non-inflammable, fl Points Of about- C. The range of '70 to 90 non-oxidizing, fusible, and flowable, free from per cent resin content is preferred-for most purcrystallinity, possessing the. ability to adhere p The W peintineleases as the Proportion firmly to metals and insulations normally used f rubber is increased, a flow point of 132 C. in electrical apparatus, and being more adhesive Characterizing 8 rubber Content of about 50 p 15 and of softer consistency than either rubber or eent- With further increase in rubber Content, resinous chlorinated diphenyl. .a discontinuity occurs, as indicated by the dotted The accompanying drawing is a graph showing e 2 in e ap T flow p i o o posiflow point-temperature relations of compositions tier-1s Containing more than 50 P Cent b r e In preparing compositions embodying our to a rubber content of approximately 90 per cent. vention, rubber may be blended with solid chlo- As rubber has no true flew Po the branch 2 rinated diphenyl containing by Weight t least could not be continued for compositions consistabout 60 per cent of combined chlorine. We s wholly or nearly wholly of b 25 prefer to use chlorinated diphenyl containing Inhke manner the Penetratien V ues Show ab- 25 about 65 per cent of chlorine. It is a solid resin normality- Compositions containing at least having aflow point f about 1 0 about 50 per cent by weight of solid chlorinated Rubber, when subjected to the ordinary flow diphenyl (of about 60 17065 per cent chlorine point test of A. S. M. standards (D36 26) content) are soft andtacky, are flowable and may does not exhibit flow without permanent change. be cast i i i i j some elasticity It softens at a temperature indefinitely above i molt-1a relativey Dug H readlly a C but when once wfiened does not return mixed with fillers, fibrous materials and the like. t The A. S. T. M. standard penetration test shows 0 p f to the compounds a penetration of about 123 mm. A composition descnbed thls apphcatwflcontaining about 25 per cent of rubber and '75 per q t the two essentlal mgredients of our cent of resin showed a penetration of about 228 eempesltlen y be d in Various P p n mm. A composition containing about 15 per cent In ac ordance with the properties desired in the of rubber and 85 per cent of the resin showed a product, we prefer for most purposes to employ penetration of about 173 mm. The resin showed 4 the polyphenyl compound in a proportion equal zero penetration. 40 to, or preponderating over, the proportion of rub- In the prepa of compositions embodying her by weight. Compositions, made by blending our invention the rubber is homogeneously to 95 partsof chlorinated polyphenyl (containing blended with the polyphenyl compound in any to per cent combined chlorine) with 50 to 5 suitable manner, Preferably y e So ut on of 45 parts by weight of rubber, as shown by bra both ingredients in a solvent. Each constituent 45 of t graph, have flow point which i lower is dissolved separately in a suitable solvent liquid, than that of the chlorinated diphenyl constituent, r xam carbon tetrachloride. benzened lower t t oftening point of b The solutions are mixed and the solvent is evap- These compositions, furthermore, are non- Oratedlline and are characterized by a softness In some cases the solid po p e y c mpounds of consistency and tackiness (or adhesiveness) ay c t m d y radicles a d st l be useful not possessed by either constituent. All of the for the purposes of our invention. 1for egraihple, compositions embodying our invention are hothe phenyl radicles may be lin ed together mogenous and manifest the properties of soluthrough carbon radicles such asmethyl, ethyl, 55 tions. carbonyl, or the like. Such compounds are de- 55 The latter property is of especial value in electri-' cal apparatus in which the sensitivity of ordinary rubber to ozone generated by electric discharges has been a serious problem;

The gases produced by the thermal or electrical compositions of compounds embodying our invention are non-inflammable when the percentage of halogen in the compound is sufliciently high. Thermal decomposition of rubber results in the production of hydrogen and other inflammable gas.- Halogenated compounds, such as chlorin-- ated diphenyl, supply chlorine or other halogen which combines with the hydrogen evolved from I the rubber to form a non-inflammable gas.

Hence, if a. sufliciently highly chlorinated polyphenyl compound is employed and especially if such compound ispresent in preponderating proportions, thenthe gases given off upon decomposition of the blended product are non-inflammable.

While the compositions embodying our invention are not limited to any particular field of application, they are of especial utility in the field of electrical insulation. These compositions may be used in conjunction with other insulating materials, as for example asbestos, cotton, linen or paper. The compositions embodying our invention may be applied upon fibrous sheet material, such as cloth or paper, or introduced into the fibers thereof by impregnation. They may be applied in the liquid state or whilein solution. Asbestos may be mixed therewith in various known ways, for example, when the composition is fused or in solution, or the asbestos may be mechanically admixed with the product during the millingand mixing operation incident to its preparation. In some cases it is desired to add to the composition a vulcanizing agent, or modifying material. It is possible to add to the composition fillers, pigments, resins, gums, or other addition agents as now understood in the art of compounding rubber.

The compositions embodying our invention are of especial utility for use as filling compounds in potheads and cable joints. The adhesiveness 01' stickiness of these new compositions, especially to metals, (a property not possessed by either-ingredient) is of importance in potheads and cables where it isimportant that the insulation should not crack away from the conductor which it protects and insulates, asotherwise voids or spaces would be-formed, the gas in which would beeasily ionizable and cause electric breakdown. The high viscosity of the new compositions above their flow points also is advantageous. When liquefied, they will be retained by impregnated devices. Asphalt, petrolatum and pitches, by contrast, crack away at low temperatures and have in comparison much lower viscosities than the present new composition at temperatures above their flow .points.

Although in the manufacture of the composi-- tions of our invention the chlorine compounds of diphenyl, or the like, are'of particular interest,

other halogens; such as bromine and iodine, may on suitable occasion be substituted for the chlorine, wholly or in part.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. Fusible, plastic, homogeneous and tacky electrical insulation consisting of rubber and chlorinated, diphenyl, the latter. being present in an amount materiallygreater than per cent and materially less than 100. per cent by weight, the chlorinated diphenyl containing at least about per cent chlorine.

2. Homogeneous electrical insulation which is plastic, adhesive, and fusible, consisting essentially of about to.90 parts-by weight of chlorinated diphenyl containing at least 65 per cent chlorineand about 30 to 10 parts by weight of rubber.

' 3. Homogeneous electrical insulation consisting by weight of aboutto parts of chlorinated diphenyl (60 to 65 per cent chlorine) and 25 to 15 parts of rubber, said compositions being characterized by tackiness, non-inflammability, resistance to ozone, non-crystallinity, fusibility with a flow point of about 72 C., and penetration test values within a range of about 173 to 228 mm.

4. Homogeneous fillings for electric pothead and cable joints consisting essentially of rubber and solid chlorinated diphenyl, the latter being of at least about 60 per cent chlorine content, said compositions being characterized by fusibility, non-infiammability, adhesiveness and freedom from crystallinity, and a soft consistency which by the A. S. T. M. standard test is characterized by penetration values within the range of about 123 to 228 mm.

- FRANK M. CLARK.

JOHN H. KOENIG. 

